<template>
  <div class="spec-preview">
    <img :src="defaultImg.imgUrl" />
    <div class="event" r @mousemove="move"></div>
    <div class="big" >
      <img :src="defaultImg.imgUrl" ref="big"/>
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuInfo"],
  mounted() {
    this.$bus.$on("changeDefaultIndex", this.changeDefaultIndex);
  },
  data() {
    return {
      defaultIndex: 0,
    };
  },
  methods: {
    changeDefaultIndex(index) {
      this.defaultIndex = index;
    },
    move(e) {
      //蒙版
      const maskElement = this.$refs.mask;
      const bigElement = this.$refs.big;
      const masklocation = {
        left: e.offsetX - maskElement.offsetWidth / 2,
        top: e.offsetY - maskElement.offsetHeight / 2,
      };

      if (masklocation.left <= 0) {
        masklocation.left = 0;
      } else if (masklocation.left >= maskElement.offsetWidth) {
        masklocation.left = maskElement.offsetWidth;
      }
      if (masklocation.top <= 0) {
        masklocation.top = 0;
      } else if (masklocation.top >= maskElement.offsetHeight) {
        masklocation.top = maskElement.offsetHeight;
      }
      maskElement.style.left = masklocation.left + "px";
      maskElement.style.top = masklocation.top + "px";

      //放大镜
      bigElement.style.left = -2 * masklocation.left + "px";
      bigElement.style.top = -2 * masklocation.top + "px";
    },
  },
  computed: {
    imglist() {
      return this.skuInfo.skuImageList || [];
    },
    defaultImg() {
      return this.imglist[this.defaultIndex] || {};
    },
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>